Electrode holders for electric smelting furnaces and method of operating the same



N. J. HAAVIK 2,845,468 ELECTRODE HOLDERS FOR ELECTRIC SMELTING FURNACES July 29, 1958 7 AND METHOD OF OPERATING THE SAME Filed April 3, 1957 5 Sheets-Sheet 1 2% 0 m Ta N m m WM 1.4M w YMW m N July 29, 1958 .N.-J. HAAVIK 3 ELECTRODE HOLDERS FOR ELECTRIC SMELTING FURNACES AND METHOD OF OPERATING THE SAME. Filed April 3, 1957 s SheetsSheet 2 W" i 37 v H1 I If H n In I INVENTOR Mlg lz fiaufi aal lk ,5 ATTORNEYS Jlily 29, 1958 N. J. HAAVIK 2,845,463

ELECTRQDE HOLDERS FQR ELECTRIC SMELTING FURNACES AND METHOD OF OPERATING THE SAME 5 Sheets-Sheet 3 Filed April 5. 1957 Illl III] III INVENTOR Ah iii/10W final/1K Ml aa,

ATTORNEYS ELECTRODE HOLDERS FOR ELECTRIC SMELT- ING FURNACES AND METHOD OF OPERAT- ING THE SAME Nils Johan Haavik, Oslo, Norway, assignor to Elektrokemisk A/S., Oslo, Norway, a corporation of Norway Application April 3, 1957, Serial No. 650,461 Claims priority, application Norway April 11, 1956 Claims. (Cl. 1316) This invention relates to a particular type of electrode holder for electricsmelting furnaces whereby the electrode can be lowered from time to time without at any time releasing the pressure of the electrode holder on the electrode. Thus, when using this particular device it is no longer necessary to release the pressure of the holder to let the electrode slip for a limited distance through the electrode holder, or to force it through the holder by positive pressure.

Broadly speaking, this invention involves the use of an electrode holder in which the pressure on the electrode is transmitted to the electrode by three or more clamping units or pressure elements which are pressed against the electrode and which are suspended from the furnace casing either individually or in groups. Means are then provided of a mechanical nature (which is intended to include hydraulic or pneumatic means) whereby a part of the pressure elements may be moved relative to the other pressure elements. By moving half or less than half of these elements at a time, they can be caused to slide upward relative to the electrode for a limited distance without moving the electrode. After sufficient of these pressure elements have thus been raised, so that the frictional engagement of the remaining pressure elements is not sufficient to support the electrode, the mechanisms whereby the separate elements were raised are released. The electrode will then slide through the remaining stationary pressure elements without the necessity of the pressure on any of the elements being reduced. At the same time the pressure elements which had been raised will move down with the electrode until they return to their original position.

The important thing about this operation is that when any pressure elements are raised relative to the electrode, the elements so raised must be a small enough proportion of all the elements so that the electrode will not be raised by their movement. It is also usually essential when using single acting elements that the raising of the individual or group of elements be repeated at least twice (and may be repeated more often) so that the proportion of such pressure elements that is finally brought up to the raised position is great enough so that the remaining pressure elements that have not been raised will not be sufficient to support the weight of the electrode. By meeting these conditions the electrode itself will not be moved when the pressure elements are brought up to the raised position but the electrode will slide down when the aggregate groups of raised electrodes are released; and all of this will occur without the necessity of releasing the pressure of the pressure elements on the electrode.

The pressure elements may be of any desired kind such as clamps used with a pressure ring or other types of known pressure elements which are pressed against the electrode by hydraulic or pneumatic means. It is, of course, necessary that if the pressure elements are directly interconnected, such interconnection must permit of some relative vertical movement between them.

While ordinarily it will be sufiicient to permit the r ce electrode to slide by its own weight through some of the pressure elements, the mechanism for controlling the movable elements may be double-acting whereby these elements may be forced down to assist the movement of the electrode. Such downward forcing movement may be particularly useful if the device is employed with inclined or horizontal electrodes.

This invention can most readily be illustrated by showing its employment with the type of electrode holder using a pressure ring and a relatively large number of clamps pressedby such ring against the electrode. Such a form of the invention is illustrated in the accompanying drawings in which- Fig. 1 is a side View of an electrode holder embodying my invention showing the parts in normal position and with the pressure ring and one clamping member shown in section;

Fig. 2 is a sectional view on line 2-2 of Fig. 1';

Fig. 3 is a view corresponding to Fig. 1 showing the parts in position just before the electrode is lowered; and

Fig. 4 is a detailed view showing a modified form in which the contact elements are interlocked in such a way as to permit only limited relative movement.

In the drawings, 10 is the electrode and 12 is the fixed suspension casing. 14 is the pressure ring which clamps the pressure elements against the electrode. In this example the pressure elements are in two classes: 16, 18, 20 and 22 are fixed members pressed directly against the electrode by the pressure ring 14. Pressure elements 24, 26, 28 and 30 (see Fig. 2) are movable members pressed against the electrode through spring housings 32 carried by the pressure ring 14. Each of these housings contains a spring 34 which forces a roller 36 against its pressure member. As shown in the sectional portions of Figs. 1 and 3 the movable contact members are provided with grooves or recesses for the rollers as indicated at 38. The pressure of the springs 34 can be adjusted by externally threaded plugs 37.

It is to be understood that each of the pressure elements, whether fixed or movable, is water-cooled and the cooling pipes are indicated at 40 and 42. The fixed pressure elements 16, 18, 20 and 22 are directly suspended from the suspension casing 12 by links 44. The pressure ring is suspended from this casing by rods 46 and the movable pressure elements 24, 26, 28 and 30 are suspended from the suspension casing 12 by the pneumatically operatedv cylinders 48. Pneumatic connections for operating one of these cylinders are indicated in Fig. 1 in which pipe 50 is used for admitting pressure to raise the plunger of the cylinder and pipe 52 may be used for introducing pressure, if positive downward pressure on the plunger is desired for any particular reason.

In'operating this particular embodiment of the invention it is understood that the electrode (which may forv example weigh 10 tons) is secured against sliding by a safety margin which may, for example, be 60%. Since there are eight clamps, the total clamp pressure multiplied by the friction coefiicient must accordingly be at least of the electrode weight or 16 tons, that is, each clamp is capable of carrying 2 tons or 20% of the actual electrode weight.

When it is desired to lower an electrode, the movable clamps are pulled up by their cylinders 48 either singly or in pairs. From the facts given, when two of these clamps are raised they are capable of supporting only 40% of the weight of the electrode and therefore the electrode will not move when they are raised. After all four of the movable clamps have been raised, the electrode is still supported by the full clamping pressure. However, if now the lifting forces in the cylinders 48 are released, the electrode will be supported only by the four fixed clamps, and since on the figures given these are capable of supporting only 80% of the weight of the electrode, the electrode while still under the full clamping pressure will slide down through these fixed clamps. This movement will continue until the plungers in the cylinders 48 reach the bottom limit of their-movement when the electrode'will again be supported by all eight clamps and the carrying forces will again be 16l)% of the theoretical required.

In the particular embodiment of the invention shown, the method of transmitting electric current to the electrode is not illustrated, as that may be done in any wellknown manner, either through the clamps or by separate mechanism.

In Fig. 4, 50 is a movable clamping element and 53 and 54 are fixed clamping elements. In this showing the movable element 51 is provided with projections 56 with spaces 58 between them. In the same way'the fixed contact elements 53 and 54 are provided with projections 60 with spaces 62 between them. It will be noticed that the spaces 58 and 62 are higher than the height of the projections 56 and 60, so that the movable contact member 51 can have some but only limited vertical movement relative to the fixed contact members 53 and 54.

By this arrangement the extent of movement of the movable contact members can be controlled independently of the permissive movement of the plungers in the cylinders 48. Such an arrangement which may limit the amount of movement so that the electrode may be lowered for example only a few centimeters at a time is particularly valuable with electrodes of the continuous or Soederberg type, as this will insure controlled baking of the electrode and an even and gradual raising of the baking Zone in the electrode. It is also valuable in connection with automatic control.

It is understood that the example given is intended only by way of illustration and that the principle of operation here described may be employed in many modifications without departing from the spirit of my invention.

What I claim is:

1. The method of lowering an electrode for an electric furnace which electrode is suspended by a plurality of pressure elements, which comprises raising a part of such elements relative to the electrode, which part is a small enough proportion of all the elements so that the electrode is not thereby raised, then raising another part of such elements which is also a small enough proportion of all the elements so that the electrode is not thereby raised, continuing such separate raising of elements until the proportion of elements that remains unraised is insufficient to support the electrode, and then simultaneously releasing the raised elements to permit them to sink to their original position whereby the electrode is permitted to slide down through the unraised pressure elements without the necessity of releasing the pressure on the pressure elements. I

2. A method as specified in claim 1 in which about half the pressure elements are raised in at least two operations.

3. A holder for an electrode in an electric smelting furnace comprising a series of more than two relatively movable pressure elements, an electrode in the holder,

means for pressing such elements against the electrode to hold the electrode suspended, means for raising a part of such elements without raising the other elements of the series and means for also separately raising another part of such elements without raising the remaining elements, such raising mechanisms being adapted to be released simultaneously to permit the electrode and the raised elements to sink down relative to the unraised elements.

4. A structure as specified in claim 3 in which the pressure elements are pressed against the electrode by means of an external pressure ring provided with roller elements that are yieldably pressed against the pressure elements which are to be raised, whereby the friction between such movable elements and the pressure ring is reduced.

5. A structure as specified in claim 3 in which at least half of the pressure elements are adapted to be moved relative to the remaining pressure elements.

6. A structure as specified in claim 3 in which the means for moving the pressure elements is mechanically operated.

7. A structure as specified in claim 6 in which the means for moving the pressure elements is double acting.

8. A structure as specified in claim 3 in which the fixed pressure elements and adjacent movable pressure elements have cooperating projections and spaces so that the relative movement of such elements is limited.

9. The method of lowering an electrode for an electric furnace which electrode is suspended by a plurality of pressure elements, which comprises raising a part of such elements relative to the electrode which part is a small enough proportion of all the elements so that the electrode is not raised thereby but which is also a large enough proportion of all the elements so that the unraised elements alone do not exert sufficient friction to support the electrode, and then releasing the raised pressure elements to permit them to sink to their original position whereby the electrode is permitted to slide down through the unraised pressure elements without the necessity of releasing the pressure on the pressure elements.

10. The method of lowering an electrode for an electric furnace, which electrode is suspended by a plurality of pressure elements, which comprises raising a part of such elements relative to the electrode which part is a small enough proportion of all the elements so that the frictional engagement of such raised elements is not sufficient to overcome the weight of the electrode and thereafter positively forcing down the raised elements so that the frictional engagement of the raised elements in addition to the weight of the electrode will cause the electrode to move downwardly through the unraised pressure elements without the necessity of releasing the pressure on the pressure elements.

References Cited in the file of this patent UNITED STATES PATENTS 2,668,183 Foyn Feb. 2, 1954 2,753,388 Bjerkas July 3, 1956 2,778,865 Konasgaarden Jan. 22. 1957 

